<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>el:挂载点</title>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>

    <div id = "app">
        {{ message }}
    </div>

    <script>
        var app = new Vue({
            // 可选id,class,div
            // 推荐用id

            // el不可用于body
            el:"#app",
            data:{
                message:"你好"
            }
        })
    </script>
</body>
</html>